1. Field of the Invention:
The present invention relates, in general, to internal combustion engines and hot gas or Stirling engines and, more specifically, to combined internal combustion and hot gas engines.
Hot gas engines, such as Stirling engines, utilize repetitive contraction and expansion of heated and cooled intercommunicating gas volumes. In a typical Stirling engine, heat is supplied to a working fluid disposed in a hot, expansion chamber in an engine. Due to the absorbed heat, the working fluid expands and is moved by a reciprocal displacer through a regenerator where it gives up heat to a cold chamber in the engine. Subsequently, the displacer moves the fluid back through the regenerator to the hot chamber to repeat the cycle. Heat is, thus, employed in a Stirling engine to produce work. However, the amount of heat required for efficient operation is high thereby requiring costly high temperature metals. Further, multiple heat exchangers are required which add to the cost and complexity of the engine.
In internal combustion engines, large amounts of heat are wasted. Most of the heat generated by the combustion of fuel is radiated through the engine block, transferred away through the radiator or expelled as hot exhaust gasses. Except for isolated use to pre-heat the fuel, drive a compressor or supercharger, or heat an associated vehicle passenger compartment, such heat is wasted thereby lowering the efficiency of such internal combustion engines.
Attempts have been made to combine an internal combustion engine with a hot gas or Stirling engine in a compound engine which makes better use of the heat generated during fuel combustion. However, certain of such compound engines utilize separate, side-by-side internal combustion cylinders and hot gas cylinders. This results in a large, bulky, heavy engine. Other compound engines utilize only a portion of the heat generated during combustion and thereby have only a moderate increase in efficiency over a conventional internal combustion engine.
Thus, it would be desirable to provide a combined internal combustion and hot gas engine which has increased engine efficiency. It would also be desirable to provide a combined internal combustion and hot gas engine which has a small, compact construction. It would also be desirable to provide a combined internal combustion and hot gas engine which may be produced in any engine configuration, including any number of cylinders and cylinder arrangements.